The government of Iraq will prohibit Exxon Mobil Corp. (NYSE: XOM) from participating in the May auction of new leases because the US company last year signed six leases for exploration in Kurdistan without the central government’s consent. The Kurdistan Regional Government claims the right to offer leases in the autonomous region, a claim hotly disputed by the central government.

The Iraqi government is auctioning 12 exploration blocks and 47 other companies have been qualified to bid in the leasing round, currently scheduled for May 30-31. Among those companies welcomed into the auction are Royal Dutch Shell plc (NYSE: RDS-A), a partner with Exxon in developing Iraq’s massive West Qurna field.